Brake drum



Sept. 23, 1924. 1,509,292

F. D. HANSEN ET AL BRAKE DRUM Filed April '7, 1924 2 Sheets-Sheet 1 Sept. 23 1924. magma F. D. HANSEN ET AL BRAKE DRUM Filed April 7, 1924 2 Sheets-Sheet 2 g Q M Mw MAW/i Patentfi Sept. 1924.. I

Para

rmrzarcx 1). mean we HERBERT w.

1 11mm; or MILWAUKEE, w1soo1wsm,as-

SIGNORS 1'0 FEDERAL PRESSED STEEL COMPANY, OF MILWAUKEE, WISCONSIN, A.

1 CQBPQBATION OF, WISCONSIN.

pnaaxanam Application filed ril 7, 1924.. Serial no. 7%,767.

-T o all whom it' may mm:

Be it known thatwe, Fnnnmuox D. HAN- SEN andjHERBnR'r W. TINKER, both citizens of the United States, and residing at Milwaukee, county of Milwaukee, and State of I Wisconsin,'have invented certain new and useful lmprovements in Brake Drums, of I which the following is a specification.

' In the manufacture of brake drums, which.

are attached to road-wheels and other parts of automobiles and the like, discs are cut or punched from a sheet or strip of steel of the required thickness. The discs are placed in a very powerful compression die, which cups the peripheral portion of each disc over to form the annular flan'geofthe drumwith which the frictional material of the brake is adapted'to contact 'toeflect the proper brakaction of the vehicle. When the drums are. taken from the die their webs are bowed slightly outwardly, because in'the pressing o eration the webs are n'ot'pressed flat, al-

t ough the bottom faceof the punch may be perfectly flatr We "attribute this bowing. action to the fact that the edge of the inner die member engages the fillet .or cornerradiiis at'the juncture of the webs and their flanges and as this filletjor radiusisnot sharply definedthebottoin face of this die member-does not press-.as'firmly against the web as it does against .the'radius. The bottoms also tend; to spring outwardly. due to some resiliency in liht881 s The drums are next placed in another die forthe purpose.

of the web perfectly flat or. giving it a slight'concavity, that is pressing theweb shghtly inwardly. past .the center of the ptllane in which'thelweb would aware it flat. f

many cases, it isnecessary-to subiectjithe drums to the action of the second-drum'sev- "e'ral times in ordertofgive them" theprop'gr.

concavity or; flatness, as the *c'a'sef'maywithin the small'limits' required 'or specified by automobilexcompanies iorothers. "It is.- recog'uizedby these."'skil1ed in the-art, that it ,isiiiifiieult andinmany instances impose; Bible, the; brake,i,drums--so that the; brake flanges. arejround 'or concentriql that is eircular within the' required limits,xand. so

that the web is symmetrical throughoutandi fre eeifrom defective or distortive swells or bulges. Theweh of-the drum, when-up We findtliat usually these strains are 'is non-circular or out of round and the. webs have such large bulges or swells oaus-.

ing the eccentricity, that it is necessary to hammer the bulges with a very hammer, to bring the flanges within the acceptable limits of eccentricity. In some instances this cannot be done andthen the brake drums are scrapped. We believe that the difliculty in securing drums which have their flan s concentric and their webs symmetrical is us to the fact that during the pressing or forming operation of the discs to cup them to theirdrum -shape unequal strains and stresses are set up in the steel and the excess material in the webs,'giving the webs their convex or bowed-form, exerts a radial force outwardly tending to distort or throw the flange 7 eatest and cause the maximum distortion 1n the .directionin which the steel has beenrolled,

that is in the direction'ofthe gram .of the "steel, so'that' the diameter of the-drum is slightly. greater in this direction than it is in the transverse directiom'th'ereby'tending to orm; i-The distortive swells or bulges in t e web alsofi seemf-t'o' be. along this greater d1- I subsequent die operation, explained-ab0v,1insome cases tends to bung 'tjhe flange i'tow ard concentricity,.-that 1s to say, toward true circular-or round form but this cannotialways. be accomplished and usually not within-closelimits: The degreeof eccentricitythatthe-extent of deviation fromv the true circular" or a ound form depends u on certain characteristics of or conditions 1n the steel; but, as isfwell known by experts versed inisfteel making, though not ent distributed "of the drum out of concentricity.

' thorough inspection of the drums, the correcting of defects. and scrapping of drums which are badly defective materially increase the cost of the drums.

' The principal object of our invention is to provide the webs of steel brake drums with ridges or ribs, preferably radiating ones, in order to more equally distribute the stresses and strains and cause the flanges to be substantially truly concentric and the webs to be substantially perfectly symmetrical. Other advantages of our invention are that the drums are strengthened, and careful tests and inspection are not necessary, thus reducing the cost of manufacture. Still further advantages of our invention will be pointed out hereinafter.

Referring to the drawings, Fig. 1 illustrates a brake-drum after it has been cupped or formed in and removed from the forming press or compression die; Fig. 2 is an inside elevation of a brake drum embodying our invention; Fig. 3 is a sectional view taken as on the line 3-3 of Fig. 2; and Fig. 4 is a view similar to Fig. 2 but shows a m'odi fied form of embodiment of our invention.

In manufacturing the drum embodying our invention, the disc of steel is pressed or formed in a compression die to the form shown in Fig. 1, in the .same manner as drums have been heretofore pressed. In this view we have somewhat exaggerated the convexity of the web of the drum in order to illustrate moreclearly the general contour of the pressed drum. The hub or central opening 6 andbolt-holes 7 are then punched in the web and we next put the drum in 'a suitable die and bump it (that is impart to its web a sharp powerful blow) to give its web the proper concave form and press ribs 8 therein. We preferably form the ribs by depressing the metal inwardly. that is on the'inner side of the web, so that they do not interfere with or engage the spokes or wheel hub when the drum is attached to the wheel. The ribs are also preferably tapered so that they are of greater depth at their inner ends than at their outer ends, and hence take up the maximum amount of metal adjacent the hub opening 6 and progressively less outwardly. While we prefer that the ribs shall be straight yet they maybe curved, as, for example, illustrated in Fig. 4, or they may be of any other desired and feasible form or shape. It will be observed in Fig. 4 that the outer bolt holes 10 are radially out of alignment with, or radially between the inner bolt holes 7 and this is made practical by deflecting the outer portions of the ribs.

We -find that by forming these ribs in the webs of the drum, that the unequal strains and stresses, referred to above, are either equally distributed, neutralized or eliminated. The ribs take up the surplus or excess metal in the web (which excess gave the web of the drum its initial bowed out contour or convexity) and We believe that pulling or inwardly directed forces or strains from the periphery towards the center are set up and they tend to neutralize or counteract the outward strains or forces which seem to be existent in the drum be fore the ribs are formed in its web. This equalization or elimination of the deforming or distorting strains by the formation of the ribs brings the brake drum flange to its proper true concentrici-ty and at the same time the'web is made perfectly symmetrical throughout. We have found by actual demonstration that it is only necessary to bump drums by our method once and that the flanges are much more concentric and the webs much more symmetrical than unribbed drums made from exactly the same sheet or strip ,of steel. It is not necessary to test our drums for concentricity or-symmetry or subject them to rigid inspection as the product is uniform and substantially perfect. Thus consider- ";able saving in the cost of manufacture is effected. Furthermore, we have discovered "that the ribs, either due to the equal distribution of the strains and stresses or for some other reason, increase the strength of the flanges so that they more readily resist distortion or bending, and this is highly important as they are subjected to considerable force when the braking efiort is applied to them, and also to rough handling and use in transportation and by workmen in the factories where the drums are assembled on the automobiles. It will also be obvious that-the ribs strengthen the webs of the drums radially and axially and that the ribs increase the width of the bearing surface or edge of the hub opening 6 on the barrel of the wheel-hub, as the ends of the ribs form projections 10 as viewed in Fig. 3. In securing the brake drum to a wheel, the web of the brake drum is drawn up tightly against the flange of the hub by means of boltsextending through the openings 7 between the ribs, and as the segments between the ribs are-comparatively narrow adjacent the holes, and separated by the grooves formed by the. ribs. the web of the drum is drawn more easily and equally against the'wheel and the ribs prevent the web from springing out past its center plane, (after the fashion of the bottom of a tin dish pan) as is the case in some instances with unribbed brake drums.

preferred form' of embodiment of our invention as a brake drum with a concave web and radiating ribs pressed inwardly of tapering formation, it is to be understood that our invention is applicable to brake d ums having a perfectly flat web throughout or a convex web and that theribs-may not necessarily extend radially or -may be pressed outwardly, or may be of uniform depth from one end to the other.

We claim:

1. A brake drum formed of steel of uniform thickness, having a brake flange and a web provided with ressed-in ribs adapted to impart substantiaily true concentricity to said brake flange.

2. A brake drum formed of steel of uniform thickness having a brake flange and a web provided with pressed-in ribs taking up the surplus metal in the web and adapted to impart substantially true concentricity to said brake flange, and substantially perfect symmetry to the web.

3. A brake drum formed of steel of uniform thickness having a. brake flange and a web provided with pressed-in ribs of tapering depth adapted to impart substantially true concentricity to said brake flange. \Vhile we have shown and described the 4:. A brake drum formed of steel of uniform thickness having a brake flange and a web provided with ribs extending radially from a central opening in the web and of tapering depth to take up the surplus metal and adapted to impart substantially true concentricity to the "flange and substantially perfect symmetry to the web. Y

5. A brake drum formed of steel of uniform thickness having a' brake flange and a slightly concave web provided with pressedin ribs adapted to impart substantially true concentricity to said brake flange and strengthening the same.

6. A brake drum formed of steel of uniform thickness having a brake flange and a slightly concave web provided with pressedin radlating ribs taking up the excess metal in the web, the ribs being of tapering depth and adapted to impart substantially true concentricity to said flange and substantially perfect symmetry to saidweb, and part of the ribs being deflected to accommodate bolt holes in the web.

FREDERICK D. HANSEN. HERBERT W. TINKER. 

